Date: Wed, 22 Aug 2007 14:47:37 +0200
From: Andrea Arcangeli <andrea@suse.de>
To: Andi Kleen <andi@firstfloor.org>
Cc: "Jeffrey W. Baker" <jwbaker@acm.org>, linux-kernel@vger.kernel.org,
       linux-mm@kvack.org
Subject: Re: huge improvement with per-device dirty throttling
Message-ID: <20070822124736.GQ13915@v2.random>
References: <1187764638.6869.17.camel@hannibal> <p733aybzv6e.fsf@bingen.suse.de>
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On Wed, Aug 22, 2007 at 01:05:13PM +0200, Andi Kleen wrote:
> Ok perhaps the new adaptive dirty limits helps your single disk
> a lot too. But your improvements seem to be more "collateral damage" @)
> 
> But if that was true it might be enough to just change the dirty limits
> to get the same effect on your system. You might want to play with
> /proc/sys/vm/dirty_*

The adaptive dirty limit is per task so it can't be reproduced with
global sysctl. It made quite some difference when I researched into it
in function of time. This isn't in function of time but it certainly
makes a lot of difference too, actually it's the most important part
of the patchset for most people, the rest is for the corner cases that
aren't handled right currently (writing to a slow device with
writeback cache has always been hanging the whole thing).
-
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